Manhole cover extractor

ABSTRACT

An extractor for removing a manhole cover including a central bar member. The central bar member includes first and second hooks that extend below the central bar member and first and second threaded fasteners that extend through the ends of the central bar member. The width of the central bar member may be adjusted to align the hooks with bars in the manhole cover. When the hooks are hooked onto the bars and the threaded fasteners are turned, the threaded fasteners exert downward pressure on the surface surrounding the manhole cover such that the central bar is raised and the hooks lift the manhole cover.

BACKGROUND OF THE INVENTION

Manhole covers are used in association with a variety of in-ground installations, such as sewer, water, electric, cable, telephone, water main supply valves, transformers, and the like. To gain access to the equipment/installation underneath the ground, one must first lift and then remove the manhole cover.

Typical manhole covers, such as the outfall manhole cover 30 shown in FIGS. 3 and 4, are fabricated such that the cover 30 includes two open slots 32 a, 32 b. Bars 34 a, 34 b are disposed under and extend perpendicularly to the respective slots 32 a, 32 b such that the bars 34 a, 34 b can be seen under the slots 32 a, 32 b when the cover 30 is viewed from the top. In position, the manhole cover 30 rests on and is bolted to a support ring. Due to various factors, some manhole covers 30 tend to weld to the support ring over time, thereby making already heavy covers 30 very difficult to remove.

Accordingly, there is a need in the art for a tool that safely and efficiently extracts manhole covers.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is better understood by a reading of the Detailed Description of the Invention along with a review of the drawings in which:

FIG. 1 is a schematic front view of a manhole extractor according to one embodiment of the present invention.

FIG. 2 is a schematic right side view of the manhole extractor of FIG. 1.

FIG. 3 is a schematic top view a manhole cover that may be removed by the manhole extractor of FIG. 1.

FIG. 4 is a schematic front view of the manhole cover of FIG. 2.

FIG. 5 is a schematic front view of the extractor of FIG. 1 in position to lift the manhole cover of FIGS. 3 and 4.

FIG. 6 is a schematic front view of the extractor of FIG. 1 lifting the manhole cover of FIGS. 3 and 4.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 and 2, the present invention provides a manhole cover extractor 10 for removing manhole covers 30. The extractor 10 includes a central bar member 12 that, for reference purposes, has a longitudinal axis A-A. The cross-section of the central bar member 12 may be in any shape, such as the square shape shown in FIG. 2. Other shapes, however, may be utilized, such as round and polygonal shapes.

In one embodiment of the present invention, the width of the central bar member 12 is adjustable along the longitudinal axis A-A. For example, the central bar member 12 may be formed of first and second extension members 14 a, 14 b. The first extension member 14 a is disposed within the second extension member 14 b in a sliding engagement such that the overall width of the central bar member 12 can be adjusted by sliding the first extension member 14 a in and out of the second extension member 14 b. In other embodiments of the invention, the central bar member 12 may include more than two extension members.

The central bar member 12 includes an interface mechanism extending from the central bar member 12 that can interface with a manhole cover 30 to remove the manhole cover 30 from the support ring. Exemplary interface mechanisms may include mechanical devices such as a hook or a plurality of hooks, or magnets. In one embodiment, the central bar member includes two “J-shaped” hooks 16 a, 16 b, that extend below the central bar member 12 to form such interface mechanism. These hooks 16 a, 16 b are used to separate the manhole cover 30 from the support ring, as explained further below.

The extractor 10 further includes a lifting mechanism that increases the distance between the central bar member 12 and the surface surrounding the manhole cover 30, which increasing distance results in the separation of the manhole cover 30 from the support ring. In one embodiment, a jack-screw type mechanism is used, as shown in FIGS. 1, 2, 4, and 5. For example, each end of the central bar member 12 includes a threaded fastener 18 a, 18 b, such as a bolt or screw, that extends through the central bar member 12. A mating helix 20 a, 20 b, such as a carriage nut, is provided in each end of the central bar member 12 for receiving the respective threaded fasteners 18 a, 18 b. In one embodiment of the present invention, the threaded fasteners 18 a, 18 b are long enough to extend through and below the bottom surface of the central bar member 12.

When the extractor 10 is being configured to remove a manhole cover 30, the extractor 10 is positioned over the manhole cover 30 so that the width of the central bar member 12 can be adjusted to align the hooks 16 a, 16 b with the bars 34 a, 34 b. As shown in FIG. 5, the hooks 16 a, 16 b are inserted in the slots 32 a, 32 b and hooked onto the bars 34 a, 34 b. The operator then turns the threaded fasteners 18 a, 18 b in a clockwise direction either simultaneously or with alternating turns. The operator may utilize additional appliances to supply the strength needed to turn the fasteners 18 a, 18 b, such as vice grips, pliers, and the like. When the threaded fasteners are turned, the fasteners 18 a, 18 b exert pressure into the surface surrounding the manhole cover 30, which increases the distance between the central bar 12 and the surface surrounding the manhole cover 30. In this aspect, as the central bar 12 is raised, the hooks 16 a, 16 b lift the manhole cover 30 from the support ring, as shown in FIG. 6. Once the manhole cover 30 has been lifted, the operator can move the extractor 10 and the cover 30 to a different location. Thus, the extractor of the present invention is able to safely and efficiently lift heavy manhole covers.

Certain modifications and improvements will occur to those skilled in the art upon a reading of the forgoing description. For example, it should be understood that although it is exemplary that the central bar member, hooks, and threaded fasteners be formed of steel or aluminum, any other rigid and durable material may be used. Also, it should be understood that there are various ways to make the central bar adjustable. Further, other lifting mechanisms to increase the distance between the central bar member and the surface surrounding the manhole cover include, without limitation, pneumatic lifters, electric load lifters, or other mechanical devices, such as jacks, that can impart sufficient force to increase the distance sufficient to separate the manhole cover from the support ring and surface surrounding the manhole cover. All such modifications and improvements of the present invention have been deleted herein for the sake of conciseness and readability. 

1. A manhole cover extractor comprising: a central bar member; first and second hooks that extend below the central bar member; and first and second threaded fasteners that extend through the central bar member; wherein: when the extractor is positioned over a manhole cover having at least two slots and corresponding bars; when the first and second hooks are inserted in the slots and hooked onto the bars; and when the first and second threaded fasteners are turned to exert downward pressure on the surface surrounding the manhole cover; the central bar is raised and the hooks lift the manhole cover.
 2. The manhole cover extractor of claim 1 wherein the central bar member is adjustable.
 3. The manhole cover extractor of claim 2 wherein the central bar member comprises first and second extension members, the first extension member being disposed within the second extension member in a sliding engagement such that the width of the central bar member is adjusted by adjusting the position of the first extension member within the second extension member.
 4. The manhole cover extractor of claim 3 wherein the first hook extends below the first extension member and the second hook extends below the second extension member.
 5. The manhole cover extractor of claim 3 wherein the first threaded fastener extends through the first extension member and the second threaded fastener extends through the second extension member.
 6. The manhole cover extractor of claim 1 wherein the central bar member comprises first and second mating helixes for receiving the first and second threaded fasteners, respectively.
 7. A method for operating an extractor to lift a manhole cover comprising the steps of: positioning the extractor over a manhole cover, the extractor comprising: a central bar member; first and second hooks that extend below the central bar member; and first and second threaded fasteners; inserting the first and second hooks into slots in the manhole cover; hooking the first and second hooks onto corresponding bars in the slots of the manhole cover; and turning the first and second threaded fasteners to exert downward pressure on the surface surrounding the manhole cover such that the central bar is raised and the hooks lift the manhole cover.
 8. The method of claim 7 where in the central bar is adjustable.
 9. The method of claim 8 wherein the central bar member comprises first and second extension members, the first extension member being disposed within the second extension member in a sliding engagement such that the width of the central bar member is adjusted by adjusting the position of the first extension member within the second extension member.
 10. The method of claim 9 wherein the first hook extends below the first extension member and the second hook extends below the second extension member.
 11. The method of claim 9 wherein the first threaded fastener extends through the first extension member and the second threaded fastener extends through the second extension member.
 12. The method of claim 7 wherein the central bar member comprises first and second mating helixes for receiving the first and second threaded fasteners, respectively.
 13. A manhole cover extractor comprising: a central bar member; an interface mechanism that projects from said central bar member; and a lifting mechanism to increase the distance between the central bar member and the surface surrounding the manhole cover, which increasing distance results in the separation of the manhole cover from the surface surrounding the manhole cover.
 14. The manhole cover extractor of claim 13 wherein: when the manhole cover extractor is positioned in the vicinity of a manhole cover having receptors for interfacing with said interface mechanism; when the interface mechanism is connected with receptors of the manhole cover; and when the lifting mechanism is activated to axially increase the distance between the central bar member and the surface surrounding the manhole cover; the interface mechanism connected with receptors of the manhole cover separates the manhole cover from the surface surrounding the manhole cover. 